Internal-combustion engine.



C. A. SAWTELLE.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED JULY 27,1918.

1,305, 1 72. Patented May 27, 1919.

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ZV d Z4 /6 (/5 /6 i A A TTORNEY C. A. SAWTELLE. INTERNAL COMBUSTIONENGINE. APPLICATION FILED JULY 27.1918.

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A T T6R N E Y CHARLES A. SAWTELLE, 0F DETRGIT, MICHI GAN, ASSIGNOR OFGEE-HALF T0 SARAH J.

PORTER, 0F DETROIT, MICHIGAN.

INTERNAL-COMBUSTION ENCrINE.

Application filed July 27, 1918.

To all whom. it may concern:

Be it known that I, CHARLES A. SAWTELLE, a citizen of the United States,residin at Detroit, in the county or Wayne and tate of Michigain'haveinvented certain new and useful Improvements in Internal-Combus tionEngines, of which the following is a specification, reference being hadtherein to the accompanying drawing.

This invention relates to internal combustion engines, and moreparticularly to internal combustion engines of the four cycle type.

One object OftllG invention is to provide an engine of this kind whichwill permit a substantially complete expansion, in the cylinder, of thegases produced therein by the explosion of the compressed charge,thereby utilizing the full power of the explosion and materiallyincreasing the efliciency of the engine and enabling the same power tobe secured from a smaller charge than is secured from the larger chargethat is required in the ordinal 1 internal combustion engine, whichexhausts the gases before they are completely expanded. Further, thegases,|havii1g fully expanded within the cylinder, are exhausted withless velocity, as well. as in smaller quantity, and the noise caused bythe exhaust is greatly reduced.

A further object of the invention is to automatically regulate thevolume of gas which enters the cylinder according to at mospheriopressure, or altitude, thus maintaining a uniform compression at allalti tudes.

Other objects of the invention will appear as the mechanism is describedin detail.

In the accompanying drawings Figure 1 is a sectional view takenvertically of an engine embodying my invention; Fig. 2 is a plan view,partly in section, of the engine shown, in Fig. 1; and Fig. -3 is asectional detail view of the air pump.

Incarrying out my invention I so con- .str'l'i ct the engine and socontrol the operations of the several parts thereof that the suctionstroke of the piston will create a partial vacuum in the cylinder andthat the charge of combustible mixture which enters the cylinder, atmaximum load, will be insufficient to completely destroy this partialvacuum, thus causing the charge in the cylindcr to be maintained, at thebeginning of Specification of Letters Patent.

liatented llllay 2%, lllllltl.

Serial no. 247,000.

the compression stroke of the piston, at less than atmospheric pressure.The compres sion space is reduced in size to enable the necessarycompression to be had. a result the cylinder is of sufficient capacityto permit of the full expansion of the exploded charge and the fullforce of the explosion is converted into power, the exhaust valve beingretained in its closed position until the piston has completed, orpractically completed, its power stroke.

The intake valve may be of any suitable character, but I prefer a valvewhich will be automatically opened by the suction in the cylinder,although a positively operated valve may be used. This valve may becontrolled in various ways, as by means of a yieldable controllingmedium which will yield, under the suction in the cylinder, to permitthe valve to open but which will maintain such pressure on the valvethat the latter will be moved to its seat when the combustible mixturehas entered the cylinder in sufficient quantities to reduce the vacuumin the cylinder to the desired extent, without entirely destroying thesame. By adjusting the controlling means to regulate this pressure theclosing of the valve can be timed to regulate the volume of combustiblemixture which enters the cylinder, that is, to regulate the size of thecharge.

Where the engine is intended for use at varying altitudes as in airplanework, I pre for to employ air as the controlling medium for the intakevalve. The air in the control ling device will. be subjected to the samevariations of pressure, at different altitudes, to which the mixture inthe cylinder is sub jected and will, therefore, automaticallyaccommodate itself to the needs of the engine, and will yield to agreater or lesser extent to admit a larger or smaller charge, as may benecessary to secure a uniform compression of the successive charges atdifferent altitudes.

In the present drawings I have, for the purpose of illustration, shownthe invention as embodied. in a single cylinder engine. with the intakeport at the bottom of the cylinder, and an air controlled intake valve.It will be understood. however. that engines of various kinds, eithersingle cylinder or multiple cylinder, may be used: that the intake portis not necessarily located at the bottom of the cylinder; and thatcont-rolling devices M ditl'erent kinds may be used. For eXanr pic. atnon vield able controllime device can be timed to maintain the partialvacuum in the cylinder at the beginning of the compression stroke oi thepiston. although it would not perform all. the otherfunctions of theyield able controlling: de ice.

in these (ll'HVlllQs the engine is shown as compris' 11; a cylinder Imounted on a base 2 and having' therein a piston which is connected by aconnecting rod 4 with a crank shaft 5. The cylinder has a single exhaustport 6 arranged centrally in the cylinder head, which is shown as formedintegral with the cylinder proper. [in exhaust valve 7 controls the port6 and is held normally on its seat by a spring 8 coiled about the stem 9of the valve. The exhaust valve opened in properly timed relation to themovements of the other parts of the engine by a cam 10 mounted on a camshaft 11 which is driven from a moving part of the engine. and ispreferably geared to the crank shaft in the .usual manner. The cam it)acts on a rod which is operatively connected by means of a lever 13 withthe valve stem 9. In the present construction the operation of theexhaust valve is so timed that it will not open until the piston hascompleted, or nearly completed, its power stroke. Ashore shown the sparkplug, 14, is mounted in the cylinder head at one side of the exhaustport.

In that form of the invention here illustrated the intake. port islocated near the inner end of the cylinder so that it will be uncoveredby the piston just before the latter reaches the end of its inwardtravel. and comprises a narrow slot 15 extending cirt'ruinferentially ofthe cylinder. The intake port or slot, 15 opens into a circumferentialintake chamber 16 which conununicates with a conduit 17 leading to asource of fuel sup ply. such as the "carburetor. The intake chamber 16is, preferably, gradually reduced in size toward that side of thecylinder opposite the intake conduit to provide a more equaldistribution of the combustible mixture, or fuel. The intake conduit iscontrolled by an intake valve 18 which is held on its seat by ayieldable pressure which permits it to be automatically opened b v thesuction in the cylinder but again closes it when the suction, or Vacuum,in the eylin der is so reduced by the entering mixture that it will nolonger hold the valve against the pressure of the controlling device.Obviously. bvregulating the pressure on the valve the length of timethat. the valve will remain open can be varied and the amount ofcombustible mixture, that is. the size of the charge, entering thecylinder can be regulated.

As is well understwd, in the operation of a four cycle engine theexhaust port re mains closed (lllf'lllt? the. suction stroke at thepiston. and inav much as the intake port is not uncovered until the.piston has nearly completed its suction stroke. it will be appaient thatthe pressure in the cylinder will be reduced to a very low degree. and apartial vacuum created therein, before the intake port is opened. ll henthe intake port is opened the unequal pressures will cause the intakevalve to open and the combustible mixture to pass from the intakeconduit to the cylinder. The mixture contin ues to enter the cylinderuntil the pressure therein has risen to such a point that the valvecontrolling device is able to seat. the intake valve. The pressureexerted on the intake valve by its controlling device is so regulatedthat. the valve will be seated before atmospheric pressure has beenrestored in the cylinder. tonsequently. with the engine operating atmaximum load. less than atnmspheric pressure, or a partial vacuunn willbe maintained in the cylinder at the beginning oi the next outwardstroke. the compression stroke. of the piston. To secure the necessarycompression of the. charge the compression space is made smaller than isusual in engines of similar capacity. Because of the fact that thecharge is compressed from less than atmospheric pressure a relativelylarge expansion of the exploded charge is possible within the cylinderand by retaining the exhaust valve. closed until the piston has reached,or nearly reached. the and of its power stroke the full expansion of thegases is caused to act on the piston and is converted into power, thusmaterially increasing the power derived from a given quantity of fuel,that is.f1he cfliciency of the engine.

To prevent the possibility of the combustible. mixture which remains inthe intake chamber 16 being ignited when the intake port opened on thepower stroke of the piston, l admit air to this chanrber so as to form awall of air between the combustible mixture and the intake port, or,should the air so admitted intern'iingle with the combustible mixture.to so dilute the mixture that it will not ignite. This may beaccomplished in various ways. but I prefer to provide a series of ports19 in the wall of the piston just b low its head. which ports will bebrought into alinement with the intake port on the compression stroke ofthe piston, and. inasmuch as the contents of the chamber are at lessthan atmospheric pressure, air will pass from the interior of the pistonto the chamber. This arrangement of the air ports has. the additionaladvantage of causing the air to circulate in contact. with the head ofthe piston. and thereby tending to cool the latter. It will also benoted that the combustible mixture enters the cylinder across the faceof the piston and has a cooling action thereon. As a result the pistonis very effectively prevented from overheating.

As has been stated the controlling device for the intake valve may takevarious forms, but. where the engine is intended for use at difl'crentaltitudes I prefer an air actuated controlling device. In the presentembodiment of the engine I have shown an air chamber, or cylinder, 20mounted at one side of the engine cylinder and having therein an airactuated member, such as a piston 21, which is operatively connectedwith the intake valve. Any suitable means may be provided tomaintain thedesired pressure in the air chamber. In the present instance I haveprovided an air pump which is connected with the air chamber by a pipe23 and is driven by the engine itself. As here shown the piston 27 ofthe air pum is acted upon by a cam 24, on the cam sha t 11, whichimparts the com ression stroke thereto, and by a spring 25 w iichimparts the return stroke thereto. The degree of pressure at which theair in the chamber 20 is maintained may be varied, preferably byadjusting the pump to vary the size of its compression space. The pumplhere illustrated has its cylinder head in t e form of a screw threadedplug 26 having a squared end which may be gripped by a wrench to adjustthe plug. Only a certain amount of air can enter the cylinder of thepump and by varying the size of the compression space the degree ofpressure to which this air will be subjected by the piston may bevaried. The compression of the air in the air chamber 20 willbe affectedby the different altitudes in the same manner that the compression ofthe charge in the engine cylinder is afl'ected thereby, and consequentlyany falling off of the compression in the engine cylinder will be met bya corresponding reduction of pressure in the air chamber,which willpermit the intake valve to remain open a longer time and a larger chargeto enter the engine cylinder, thus maintaining a uniform compressiontherein at all altitudes.

While I have shown and described one embodiment of my invention, I wishit to be understood that I do not desire to be limited to the detailsthereof, as various modifications may occur to a person skilled in theart.

Having now fully described my invention, what I claim as new and desireto secure by Letters Patent is:

1. In an internal combustion engine of the four cycle type. a cylinderhaving an intake port and an exhaust port, valves to control the intakeaml exhaust throughthe respective ports, a piston in said cylinder, andmeans for so controlling said intake valve that the charge will beadmitted to said cylinder near thrend of the suction stroke of thepiston and, at maximum load, will be less than the displacement of saidpiston, thereby causing a. partial vacuum to exist in said cylinder atthe beginning of each compression stroke of said piston.

2. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, valves to control the intakeand exhaust through the respective ports, a piston in said cylinder, andmeans to cause a partial vacuum to be created .in said cylinder by thesuction stroke of said piston, when said engine is operating at maximumload, and to cause a charge of combustible mixture to enter saidcylinder through saidintake port when said piston s near the end of itssuction stroke and before it begins its compression stroke, withoutcompletely destroying said vacuum.

3. In an internal combustion engine of the four c ole te a c lindcrhavin an intake y y a a: port and an exhaust port, valves to control theintake and exhaustthrough the respective ports, a piston in saidcylinder, means to cause a partial vacuum to be created in said cylinderby the suction stroke of said piston, when said engine is operating atmaximum load, and to cause a charge of combustible mixture to enter saidcylinder through said intake port, when said piston is near the end ofits suction stroke, and means for controlling said intake valve toprevent said mixture from entering said cylinder in suflicient volume toestablish atmospheric pressure therein at the beginning of thecompression 'stroke of said piston.

. 4. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, valves to control the intakeand exhaust through the respec tive ports, a piston in said cylinder,means to cause a partial vacuum to be created in saidcylinder by thesuction stroke of said piston, when said engine is operating at maximumload, and to cause a charge of combustible mixture to enter saidcylinder through said intake port, when said piston is near the end ofits suction stroke, and yieldable means for controlling said intakevalve to revent said mixture from entering said cylinder in sufficientvolume to establish atmospheric pressure therein at the beginning of thecompression stroke of said piston.

5. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, valves to control the intakeand exhaust through the respective ports, a piston in said cylinder.means to cause a partial vacuum to be created in said cylinder by thesuction stroke of said piston, when said engine is operating at maximumload, and to cause a charge of combustible mixture to enter saidcylinder through said intake port when said piston is near the end ofits suction stroke, and adjustable means for controlling; said valve toprevent said mixture from entering said cylinder in sutficient vol ie tocstaolish atmospheric pressure therein at the Ice ginning of thecompression stroke of said piston.

. 6. an internal combusti four cycle type, a c l tinder port and aneiinaust port, in said cylinder, a valve to {El .1 of :tuel tl'iroughsaid intake p rt, controlled by the pressure said c i to autonaticallyclose when a pre entered sai lllll; en

l .L: in an internal combustion the flour cycle type, a cylinder enginehaving intake port and exhaust port, a valve for,

said exhaust port, a piston in said cylinder adapted to create a partialvacuum in said cylinder upon the suction stroke thereof, a valve tocontrol the flow of fuel through said intake port and arranged to beopened by the suction in said cylinder, When said piston is near the endof its suction stroke, and a device acting on the last mentioned valveto seat the same when the vacuum in said cylinder has been reduced to apredetermined degree.

9. In aninternal combustion engine of the four cycle type, a cylinderhaving a normally closed exhaust port, a piston adapted to create apartial vacuum in said cylinder upon its suction stroke, said cylinderalso having an intake port arranged to be opened by said piston near theend of the suction stroke thereof, a valve to control the low of fuelthrough said intake port and arranged to be opened by the suction insaid cylinder, and a device to exert a constant pressure on the lastmentioned valve in a direction opposed to the suction in said cylinder.

10. In an internal combustion engine of the tour cycle type. a cylinderhaving a normallv closed exhaust port, a piston adapted to create apartial vacuum in said cylinder upon its suction stroke, said cylinderalso having an intake port arranged to be opened by said piston near theend of the suction stroke thereof. a valve to control the flow of fuelthrough said intake port and arranged to be opened by the suction insaid cylinder. and a fluid operated device to exert a pressure on thelast mentioned valve in direction opposed to the suction in said engineW tic-v. oi incl "(-1 much said in upon valve to contro' L intake portand arranged be opened by the suction in said cylinder, a controllingdevice for said last mentioned valve comprising an air clnnnbcr, amovable member 9 mounted in said chamber and connected with said valve,and means for maintaining a constant air pressure Within said chamber.

13. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, a valve for said exhaustport, a piston in said cylinder adapted to create a partial vacuumtherein upon the suction stroke of said piston, a valve to control theflow of fuel through said intake port and arranged to be opened by thesuction in said cylinder, a controlling .device for said last mentionedvalve comprising an air chamber, a movable member mounted in saidchamber and connected with said valve, and means for maintainingaconstant air pressure within said chamber, and for regulating the amountof said pressure.

14. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, a valve for said exhaustport, a piston in said cylinder adapted to create a partial vacuumtherein upon the suction stroke of said piston, a valve to control theflow of fuel through said 1530 intake ort and arranged to be opened bythe suction in said cylinder. a controlling device for said lastmentioned valve comprising an air chamber. a movable member mounted insaid chamber and connected with said valve. an air pump connected withsaid chamber, and an operative connection between said pump and saidengine.

15. In an internal combustion engine of the four cycle type, a cylinderhaving an intake port and an exhaust port, a valve for said exhaustport, a piston in said cylinder adapted to create a partial vacuumtherein upon the suction stroke of said piston, a valve to control theHow of fuel through said intake port and arranged to be opened by thesuction in said cylinder, a controlling device for said last mentionedvalve comprising an air chamber, a movable member mounted in saidchamber and connected with said valve, an air pump connected with saidchamber, and means for adjusting said pump to cause different airpressures to be maintained in said chamber.

16. In an internal combustion engine of the four cycle type. a cylinderhaving, a valve-controlled exhaust port. a piston mounted in saidcylinder and adapted to create a partial vacuum therein on its suctionstroke, said cylinder also having an inlet extending circumferentiallythereof near the inner limit of movement of said piston. and means tocontrol the flow of fuel through said inlet.

17. In an internal combustion engine of the four cycle type, acylinderhaving a valve-controlled exhaust port, a piston mounted in saidcylinder and adapted to create a partial vacuum therein on its suctionstroke. said cylinder also having an inlet near the inner limit ofmovement of said piston, means to control the flow of fuel through saidinlet, and means to cause air to pass outward through said inlet aftersaid piston has begun its compression stroke.

18. In an internal combustion engine of the four cycle type, a cylinderhaving a valve-controlled exhaust port, a piston mounted in saidcylinder and adapted to create a partial vacuum therein upon its suctionstroke, said cylinder having an inlet extending cireuniferentiallythereof and arranged to be uncovered by said piston when the latter isnear the end of its suction stroke, means to control the flow of fuelthrough said inlet, said piston having an apron provided with acircumferential series of. openings arranged to register With said inletafter said piston begins its compression stroke.

In testimony whereof I aflix my signature hereto.

CHARLES A. SAVVTE'LLE.

